Generally, chemical mechanical polishing (CMP) may be used during the semiconductor device manufacturing process to planarize various aspects of a device as it is made. For example, the formation of various features or layers in a device may cause uneven topography, and this uneven topography may interfere with subsequent manufacturing processes, such as the photolithographic process. It is, therefore, desirable to planarize the surface of the device, using known methods such as CMP, after various features or layers are formed.
Typically, CMP involves placing a device wafer in a carrier head. The carrier head and the wafer are then rotated as downward pressure is applied to the wafer against a polishing pad. A chemical solution, referred to as a slurry, is deposited onto the surface of the polishing pad and under the wafer to aid in the planarizing. Thus, the surface of a wafer may be planarized using a combination of mechanical (the grinding) and chemical (the slurry) forces.
However, the physical act of grinding a wafer against the slurry may cause excess slurry to spray up onto the various mechanical parts, windows, or walls of a typical CMP station. Over time, this excess slurry may accumulate and dry into a caked-on residue on the surfaces of the CMP station. This residue may cause various problems if left unattended. For example, residue left a mechanical arm of the CMP station, such as a slurry arm, could fall onto the polishing pad during a subsequent CMP process and cause wafer scratches. Furthermore, due to the nature of the slurry's interaction with the materials in a wafer, the residue may be toxic in nature and pose serious health risks.
It is therefore desirable to periodically clean the surfaces of a CMP station. Traditionally, this cleaning has been done manually. Typically, the CMP station is shut down, and workers manually scrub the various surfaces of the station clean. These maintenance downtimes create inefficiencies and delays in the manufacturing process. Furthermore, the residue itself may be toxic and creates a hazardous work environment for the workers. A new system and method for a self-cleaning CMP station is provided to address these concerns.